There are a lot of problems and flakiness with using a real clipboard.
Instead we now have a :debug-set-fake-clipboard command to set a text, and use
logging when getting the contents.
Fixes#1285.
Otherwise, if a test fails to actually put something into the clipboard, we end
up pasting "Does this work?" which could e.g. trigger a search.
When it's cleared, we at least get some "clipboard is empty" error instead.
- qtbot.waitSignal with raising=True is the default this way, so we remove the
raising=True.
- qtbot.waitSignal with raising=False stay untouched
- Some qtbot.waitSignal without raising had one added (because we don't want it
to raise)
- Some qtbot.waitSignal without raising actually should've raised, which they
do now.
